1. Field of the Invention
The present invention relates to an electric-wire connection structure of a connector and, more particularly, to an electric-wire connection structure of a connector which is arranged to connect a conductor constituting a terminal of the connector and a covered electric wire by the use of ultrasonic wave oscillation.
2. Description of Relevant Art
FIGS. 1A and 1B and FIG. 2 show a conventional example of an electric-wire connection structure of a connector (see Japanese Patent Publication No. 7-70345).
The electric-wire connection structure shown in FIGS. 1A and 1B is equipped with a first member 23 having groove portions 22 formed therein and a second member 25 having convex portions 24 formed thereon, whereby a lead wire 26 and a contact member 27 are laminated in the groove portion 22 and the convex portion 24 is applied from above onto the resulting laminate in such a way as to clamp the resulting laminate between the convex portion 24 and the groove portion 22, whereby the first member 23 and the second member 25 are welded together by the use of ultrasonic vibration.
In the electric-wire connection structure shown in FIGS. 1A and 1B and FIG. 2, a plurality of the lead wires 26 and a plurality of the contact members 27 are clamped by and between the first member 23 and the second member 25, which are formed with a plurality of the groove portions 22 and a plurality of the convex portions 24, respectively, and are welded together.
FIGS. 3 and 4 show an applied example of the above-described connection structure based on the use of ultrasonic welding to an actual connector. Namely, a cover 7 (corresponding to the above-described second member 25) is welded onto a terminal retaining portion 3 (corresponding to the above-described first member 23) protruding from a front portion of a connector housing 2 by ultrasonic oscillation. At this time, the cover 7 and the terminal retaining portion 3 are ultrasonically welded to each other with a covered electric wire 17 (corresponding to the above-described lead wire 26) and a conductor 16 (see FIG. 3) drawn out from the connector housing 2 being clamped therebetween.
Within the connector housing 2, there is generally formed a projection 14 for holding interfitting between male and female connectors. In order to form this projection 14, as shown in FIG. 7, on a first mold 28 for forming the connector housing 2 there is disposed a second mold 29 for shaping the projection 14. After shaping thereof, the second mold 29 is drawn out in the forward direction. For this reason, a mold drawout hole 15 is made open at the front surface of the connector housing 2.
In a case where the connection structure such as that shown in FIGS. 1A and 1B has been applied to an actual connector such as that shown in FIG. 4, the following problems arise.
First, as shown in FIG. 3, when an outermost side welding rib 10 is welded to the terminal retaining portion 3 both by ultrasonic vibration and by pressurizing force, the welding rib 10 is flexed to outside the structure, with the result that there is the likelihood of the welding rib 10 being deformed or broken.
Further, as the mold drawout hole 15 is left open, there is the likelihood that metal pieces will enter from this hole and in the worst case a connector terminal will be shortcircuited thereby.
Furthermore, there may be also a case where the terminal retaining portion 3 and the cover 7 are displaced from each other due to the ultrasonic vibration (this is particularly the case when the size of the covered electric wire 17 differs as shown in FIGS. 5A and 5B) with the result that a portion where no conduction can be made is produced (see FIG. 5B). To prevent this, there is also a method which ultrasonically welds the terminal retaining portion 3 and the cover 7 in a state where these members are positioned using a jig 30 as shown in FIG. 6. However, in this method, the mounting and demounting of the jig 30 are complex and further interference of it with ultrasonic waves is also likely to occur. Therefore, this method is not practical.